Technical Abstract:
The USDA-ARS has a long-term citrus rootstock breeding program in Florida, and in the past two decades the Florida citrus industry has also provided strong financial support for USDA rootstock development. Four new rootstocks have been released by the USDA in Florida over the past 12 years. These rootstocks, US-812 (C. reticulata ‘Sunki’ × P. trifoliata ‘Benecke’) , US-897 (C. reticulata ‘Cleopatra’ × P. trifoliata ‘Flying Dragon’), US-802 (Citrus grandis ‘Siamese’ × P. trifoliata), and US-942 (C. reticulata ‘Sunki’ × P. trifoliata ‘Flying Dragon’), each have some strong attributes that prompted their release and commercial interest, including outstanding fruit yield in multiple field trials with commercial scion cultivars. Current focus of the USDA rootstock program is on development of a sour orange-type rootstock with improved attributes, called SuperSour, as well as the development of rootstocks with improved tolerance to the diseases huanglongbing and citrus tristeza virus. This presentation includes data from several field trials and other tests to compare the attributes of the new rootstocks, and to identify appropriate conditions for commercial use of each. Information about the nursery propagation of the rootstocks will also be presented.